Subjects who have undergone the informed consent (IC) process and signed the approved IC form for the study will be assigned a Screen # (S1, S2, etc.). Those subjects who meet all inclusion and exclusion criteria will undergo various study procedures and then be scheduled for the unilateral periganglionic (PG) DRG injection(s) (a maximum of 3 contiguous levels) under fluoroscopic guidance to treat the targeted DRGs demonstrated to be responsible for the chronic CIBP.